'71 Johnson 50hp question

[Walker]

Pump. It has a screen in it that I guess you would call a filter.

 

[PrplGld]

'71 Johnson 50hp question

This is model #50ESL71S.<br /><br />Is the circled object a fuel filter or fuel pump? There are no wires coming to/from it. (This isn't actually my motor but mine is identicle. Mine isn't nearly as clean)<br /><br />

 

[REELSPORT]

Re: '71 Johnson 50hp question

careful when you take that screw out in the middle and dont lose your gasket.

 

[PrplGld]

Re: '71 Johnson 50hp question

Originally posted by Walker:<br /> Pump. It has a screen in it that I guess you would call a filter.

Ok, but does it really "pump"? The only source of power I could think of might be pressure in the fuel line. I'm struggling with this, please explain. I want to figure it out without taking it apart, I wouldn't be able to get it back together.<br /><br />Thanks

 

[fireman57]

Re: '71 Johnson 50hp question

Take the line that goes from the pump to the carb off. If you can blow through it then you will be taking it off anyway. Get an OEM manual and it will lead you step by step.

 

[Walker]

Re: '71 Johnson 50hp question

The only source of power I could think of might be pressure in the fuel line

There should be 3 lines to it. One to the carbs, one from the fuel tank, and the third line is what powers the pumop. It goes to a fitting on/in the crankcase. The pressure ans vacumn pulses from the crankcase make the pump work.

 

[Joe Reeves]

Re: '71 Johnson 50hp question

As all of the above, that item is fuel pump which has a fine mesh filter within the plastic cap.<br /><br />To test, have fuel supplied to the fuel pump, remove the line that leads to the carburetor(s), attach another longer line to that pump fitting so that it flows into some kind of container. Have the s/plugs removed. Crank the engine. Fuel should shoot out of the attached hose into the container.<br /><br />Are you having a problem, and if so, what is it?

 

[PrplGld]

Re: '71 Johnson 50hp question

Originally posted by Joe Reeves:<br />Are you having a problem, and if so, what is it?

I'm sorry, I wasn't clear. I don't believe there's a problem with it, I was just curious about how it worked. I think I understand know, thanks for the replies.

 

[ledgefinder]

Re: '71 Johnson 50hp question

It uses the crankcase pressure, which fluctuates.

 

[Silvertip]

Re: '71 Johnson 50hp question

On a two stroke engine, the crankcase has negative pressure (vaccum) for part of its cycle and positive pressure for the other. It's the pressure-vacuum pulsations that operate the pump. The newer EFI/DFI engines have electric pumps.